I actually find it a lot easier on mobile, because you can see all the symbols available to type without having to memorise them or have 2-4 different characters printed on each key. Gboard has almost every special character I ever need to use accessible in its two extra screens, and accented letters like êëéèē accessible by long-pressing the base letter.

Unexpected Keyboard (on F-Droid) is also fantastic for extra characters, give it a try, but I don’t use it as a daily driver because of lack of spellcheck and glide typing.